Fluid-pressure brake.



4 PATENTED MAR. 15, 1904. G. M. SPENCER & G. J. GRELLNER. I I

FLUID PRESSURE BRAKE APPLICATION FILED APR. 8, 1903.

H0 MODEL.

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UNTTED STATES Patented March 15, 1904.

PATENT ()EEIC GEORGE MACK SPENCER AND CHRISTOPHER J OS. GRELLNER, OF ST. LOUIS, MISSOURI.

FLUID-PRESSURE BRAKE.

SPECIFICATION forming part of Letters Patent No. 7 54,908, dated March 15, 1904:.

Application filed April 8, 1903. Serial No. 151,693. (No model.)

To all whom it may concern:

Be it known that we, GEORGE MACK SPEN- OER and CHRISTOPHER J OSEPH GRELL ER, citizens of the United States, resid ng in the city of St. Louis, State of Missouri, have invented, certain new and useful Improvements in Fluid-- Pressure Brakes, of which the following is a specification.

Ourinvention relates to the application of fluid under pressure acting on an intermediate medium, which in turn operates or controls the mechanism of a car or vehicle brake, together with such arrangements as will permit of the utilization of a negative pressure or vacuum acting on one side of the brakecylinder piston while the pressure is applied on the opposite side. a

The objects of our improvements are to overcome the destruction of thepump and brake cylinder by dust and destructive substances being taken into the system during the charging of the reservoirs; and we accomplish these results by means of the appliances and arrangements described in the following specification and illustrated in the accompanying drawing, in which there is shown a diagrammatic arrangement of the tank or reservoir, alternative views of a method of valve control, both on and off, and an operative double-acting brake-cylinder.

The principal features of our invention consist of a reservoir or tank 1, having a partition 2 near its center, a double-acting brakecylinder 3, and piston 4 and pump 5. As there are many ways in which the pipes or connections may be arranged without changing the novel features of our improvement, We illustrate and describe only one system.

As shown, the valve 6 is open and the brakes would be applied. In 7 the valve is closed, in which case the brake is off and the pump is in active connection.

The letters V and P when added to any part of the illustration or description will designate vacuum and pressure, respectively.

Describing the methods of valve arrangement shown, the operation of the system is as follows: The two ends or opposite sides of the piston L are connected together, in which case the pressure on each side of 7 is equalized and the brake-springs will force the piston to the position shown. When the valve is turned, as at 6, the forward or vacuum end of the cylinder 3 will be in communication with V of the reservoir 1, and the back end of 3 will be connected to P of the reservoir 1, in which case the piston 4 will be forced away from P and toward V, thus setting the brake with a force equal to the power expressed by the pressure in P plus the vacuum in V. During release the valve is returned to position 7 and the pressure on each side of i equalized, as before explained. It should be mentioned that there is a constant or regulated action of the pump 5 to keep the fluid out of V and compressed into P. As a means of providing an initial pressure of sufficient volume there is a valve 12. It is calculated'that the leakage, which is mostly inward, will keep up the pressure when once provided. There also may be provided vacuum and pressure gages 11 and 10 for convenience of determining the condition of fluid in the reservoir 1.

It will be seen that by the method of construction and arrangement described and shown one of the most serious obstacles to the use of fluid-pressure brakes on streetcars and other vehiclesthe destruction of the brake and pump cylindersis entirely overcome, as no fluid is drawn into the system during the operation of the brakes or pumps, all the fluid being retained or simply transferred from one position to another without allowing any to escape outwardly.

As a means of lubrication of the brake-piston we prefer the method shown, in which the piston 4 is provided with chambers 13 and 14, filled with some absorbent material which may retain any lubricant which may be allowed to flow into the system. The outer surface of the piston, or that portion which comes in contact with the cylinder, is provided with perforations or openings, as illustrated in 14, where the absorbent material is not shown. This method allows the lubricant to be distributed uniformly over the moving surfaces at all times.

What we claim as our invention, and desire to secure by Letters Patent, is-

1. In a fluid-pressure brake system, the combination of a pressure-chamber, a vacuumchamber, an operative piston and cylinder, means to connect opposite ends of the cylinder with each other, means to connect the the fluid from the Vacuum-chamberand force it into the pressure-chamber.

3. In a fluid-pressure brake system, an independent vacuum and pressure chamber with means to control the fluid, between opposite ends of abrake-cylinder, between the vacuum and pressure chambers and between the vacuum-chamber and one end of the brakecylinder simultaneously with the opening of the communication between the opposite end fit the brake-cylinder and the pressure-chamer.

4. In the operating of fluid-pressure brakes, means to equalize opposite sides of a brakepiston during release and means to release the pressure from one side only, during application of brakes, either into the open air or into a vacuum-chamber.

GEORGE MACK SPENCER. CHRISTOPHER JOS. GRELLNER.

Witnesses:

J. B. BIGHTER, M. G. TAYLOR. 

